CHROMATOGRAPHIC CHARGE-DENSITY DETERMINATION OF MATERIALS WITH LOW SURFACE-AREA

A new method is presented for the determination of the charge density as a function of pH for oxides. From measured pH-breakthrough curves through a chromatographic column filled with the sorbent, one can obtain the charge density by a simple integration. This method is specially interesting when classical titration experiments cannot be applied, for example, if the sorbent has a low surface area with not enough sites to be detected by common potentiometric titrations. The feasibility of the technique is demonstrated by measuring charge densities of silica and iron oxides and comparing with known data.